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07-25-2012, 08:00 PM

NEW YORK (Reuters Health) - People who are prescribed certain antibiotics for acne - even those who take them for months at a time - are unlikely to develop bacteria resistant to those drugs, according to a new study.
The finding is surprising given what researchers know about bacteria's ability to adapt to common antibiotics and become immune to their effects, the authors say in the Archives of Dermatology.
And it's particularly interesting because the bacteria the authors examined - Staphylococcus aureus - is the culprit behind MRSA, an infection that is resistant to multiple antibiotics and more dangerous and harder to treat than other non-resistant infections, they note.
"A lot of the work that we've done over the years has often shown problems with long-term antibiotic use," Dr. David Margolis, one of the study's authors from the University of Pennsylvania School of Medicine in Philadelphia, told Reuters Health.
When it comes to tetracycline, the most common class of antibiotics used to treat acne, he said that "for an antibiotic that's been around for a long time ... it's interesting to notice that Staph aureus hasn't become overtly resistant to it."
Margolis and his colleagues took nose and throat swabs from 83 patients being treated for acne at their dermatology clinic to look for the presence of staph bacteria. Close to half of those patients had been treated with antibiotics, some of them for up to a year.
Between 40 and 50 percent of all patients had staph in their throats or noses, which is consistent with the frequency in the general population, the authors note. Patients who were taking antibiotics to treat their acne were less likely to have staph bacteria - probably because the acne drugs were killing nose and throat bacteria in addition to the bacteria that cause acne, Margolis said.
Only about 10 percent of all staph bacteria the authors sampled were resistant to tetracycline antibiotics.
Using tetracycline antibiotics to treat acne did not increase the chance that a patient would have staph bacteria that tested positive for tetracycline resistance.
While most patients who take antibiotics for an infection might be on the drugs for a week or two, people with acne may take antibiotics for months or even years, Margolis said.
Because of that, there has been concern that these patients may be more likely to harbor bacteria that are resistant to tetracycline antibiotics. That would be a problem if the generally harmless staph bacteria turned into a more serious infection or if those patients spread the resistant bacteria to others.
But Dr. Guy Webster, a dermatologist at Jefferson Medical College in Philadelphia, said this paper adds to the data suggesting that the odds of acne patients getting a serious, drug-resistant infection are low.
"A lot of the public panic about treating acne with antibiotics is unwarranted, at least as far as Staph aureus and resistance goes," Webster, who did not participate in the current research, told Reuters Health.
The study "affirms what we kind of already know," Webster said. Dermatologists have long used tetracyclines in acne patients, he said, and yet they are still some of the few drugs that successfully treat MRSA.
Webster said that tetracycline resistance is still a possibility in acne patients who have long-term treatment with antibiotics. And, he said, there are other negative effects of tetracycline treatment - such as an increased likelihood of yeast infections in women taking the drugs.
Margolis added that more research is needed on the risks of antibiotic resistance when tetracyclines are prescribed to people with acne.
But at least for now, when doctors are considering treatment for acne, the risks of these antibiotics seem to be smaller than the potential benefits, Webster said.
"If you have a kid with bad acne on his face, you've got to go for the thing you know he has," rather than falling back on the possibility of an antibiotic resistant infection, Webster said. "You know he's going to have a problem with bad acne, and that acne is not nothing. (It's) not something to ignore."
SOURCE: http://bit.ly/e5SbUW Archives of Dermatology, online April 11, 2011.